Controller discovery oddity

For example, if you provision an AP using the GUI (AP Installation), and enter "aruba-master" for "host controller" under "Master discovery", the ap is provisioned with the parameter "provision-ap server-name aruba-master".

Will this AP still go through all those steps of controller discovery or will it only try querying DNS for aruba-master?

Second, if the DHCP scope provides multiple name servers, and the first is unreachable, will the AP try querying a 2nd name server for aruba-master?

I ask because I had just set up a site with a local controller and things were working well. Suddenly the AP's went down and the only culprit I know about was that access to the name servers in their DHCP scope were cut off (a sys admin applied an erroneous firewall policy on the server's software firewall).

The AP's were terminated against the local controller, but provisioned as per the above. DHCP provided a domain suffix and two name servers, and querying for aruba-master.domain.suffix resolved the master controller.

While at the moment I did not have console access to the AP's, I could see from the switch ports they were patched to that the AP's were continually rebooting (the AP's were connected to non-Aruba/non-controller switch ports).

Would lack of DNS cause an AP to reboot? And even if DNS went down, some of the AP's were on the same VLAN as a controller interface--shouldn't an ADP broadcast have located the local controller?

Eventually we got one of the name servers back--the one listed 2nd in the DHCP scope. The AP's kept rebooting. It wasn't until access to the 1st listed name server was restored that the AP's finally booted and came up correctly.

That one's a puzzler for me and I wonder what happened. I suppose it's possible a network reconfig cut the AP's access to their LMS IP and backup LMS IP and that's why they rebooted. No one fessed up, though. All I heard about (and witnessed/experienced) was the lack of access to the name servers.

Lack of DNS should NOT cause the AP to reboot. Loss of connectivity with the master controller would, however. In either event if an AP is on the same subnet as the master controller, it should be able to discover it, layer2 and reconnect to the controller's switchip.

Re: Controller discovery oddity

‎11-23-201003:43 PM

thanks, Colin. How you and the kb article describe the process is how I thought it went...then I saw that strange behavior. Evidently there was a lot of extra work going on around me that I did not know about.